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| Titel |
Airborne observations of the Eyjafjalla volcano ash cloud over Europe during air space closure in April and May 2010 |
| VerfasserIn |
U. Schumann, B. Weinzierl, O. Reitebuch, H. Schlager, A. Minikin, C. Forster, R. Baumann, T. Sailer, K. Graf, H. Mannstein, C. Voigt, S. Rahm, R. Simmet, M. Scheibe, M. Lichtenstern, P. Stock, H. Rüba, D. Schäuble, A. Tafferner, M. Rautenhaus, T. Gerz, H. Ziereis, M. Krautstrunk, C. Mallaun, J.-F. Gayet, K. Lieke, K. Kandler, M. Ebert, S. Weinbruch, A. Stohl, J. Gasteiger, S. Groß, V. Freudenthaler, M. Wiegner, A. Ansmann, M. Tesche, H. Ólafsson, K. Sturm |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 5 ; Nr. 11, no. 5 (2011-03-11), S.2245-2279 |
| Datensatznummer |
250009458
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| Publikation (Nr.) |
 copernicus.org/acp-11-2245-2011.pdf |
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| Zusammenfassung |
| Airborne lidar and in-situ measurements of aerosols and
trace gases were performed in volcanic ash plumes over Europe between
Southern Germany and Iceland with the Falcon aircraft during the eruption
period of the Eyjafjalla volcano between 19 April and 18 May 2010. Flight planning and measurement
analyses were supported by a refined Meteosat ash product and trajectory
model analysis. The volcanic ash plume was observed with lidar directly over
the volcano and up to a distance of 2700 km downwind, and up to 120 h plume
ages. Aged ash layers were between a few 100 m to 3 km deep, occurred
between 1 and 7 km altitude, and were typically 100 to 300 km wide.
Particles collected by impactors had diameters up to 20 μm diameter,
with size and age dependent composition. Ash mass concentrations were
derived from optical particle spectrometers for a particle density of 2.6 g cm−3 and various values of the refractive index
(RI, real part: 1.59; 3 values for the imaginary part: 0, 0.004 and 0.008).
The mass concentrations,
effective diameters and related optical properties were compared with
ground-based lidar observations. Theoretical considerations of particle
sedimentation constrain the particle diameters to those obtained for the
lower RI values. The ash mass concentration results have an uncertainty of a
factor of two. The maximum ash mass concentration encountered during the 17 flights
with 34 ash plume penetrations was below 1 mg m−3. The Falcon
flew in ash clouds up to about 0.8 mg m−3 for a few minutes and in an
ash cloud with approximately 0.2 mg m−3 mean-concentration for about
one hour without engine damage. The ash plumes were rather dry and
correlated with considerable CO and SO2 increases and O3
decreases. To first order, ash concentration and SO2 mixing ratio in
the plumes decreased by a factor of two within less than a day. In fresh
plumes, the SO2 and CO concentration increases were correlated with the
ash mass concentration. The ash plumes were often visible slantwise as faint
dark layers, even for concentrations below 0.1 mg m−3. The large
abundance of volatile Aitken mode particles suggests previous nucleation of
sulfuric acid droplets. The effective diameters range between 0.2 and 3 μm with considerable surface and volume contributions from the Aitken and
coarse mode aerosol, respectively. The distal ash mass flux on 2 May was of
the order of 500 (240–1600) kg s−1. The volcano induced about 10 (2.5–50) Tg
of distal ash mass and about 3 (0.6–23) Tg of SO2 during
the whole eruption period. The results of the Falcon flights were used to
support the responsible agencies in their decisions concerning air traffic
in the presence of volcanic ash. |
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